I have seen cases of severe depression that seem to be entirely chemical where psychotherapy is less effective than medication. But, this is very rare, most individuals with depression that I see respond very well the therapy because they are motivated to feel better. The individuals that I have seen that didn't respond well to therapy didn't seem that motivated towards therapy and most were looking for a chemical cure and therapy was something they were going to because they had to. Others appeared to suffer from a chemical imbalance. And, as is the case with Individuals with Bipolar disorder, they had no choice but to endure a mental illness that subjected them to extreme tortuous mood swings. In cases such as these therapy can mitigate the pain and help the individual to accept the hand that has been dealt them. Intention therapy can help the individual see that the intention to not feel the depression causes them to push it away and not accept in. This pushing away actually keeps it there because they are telling themselves "I can't feel this" and they tighten up around the pain. We tend to tighten up around physical and emotional pain. Often, it's not the pain itself but our tightening around it that makes it seem unbearable. In almost all case of depression I have seen the intention to wall off the pain is there.
In most cases of depression that I see, the ones that respond well to treatment there is clearly an intention that keeps the individual feeling "depressed". The intention of depression is usually an intention towards past selfhood. It is an intention to go back in time, to a happier, better, self-accepting place. It is an intention perpetually away from the current moment toward a time in the past that represents a time before some significant loss. It is an intention toward a lost self that went along with that past time. Very often the memory of the place in time to get back to gets lost but the intention and the emotion that comes from refusing to accept this current life, and this current self remains. The intention of depression actually starts out as an intention towards happiness, past happiness, but nonetheless happiness.
Individuals who are depressed color their whole experience as depression. When asked they often can't remember the last time that they were happy. But, if you talk to them enough and are around them enough you find that they will laugh and smile and at times appear happy. They don't want to see this. They are denying their own happiness. The intention toward depression for its own sake seems to take hold at some point. The mind puts out any better place in time, it denies that there ever was such a thing. The intention to stay in depression is still known logically by the unconscious mind but the individual has no real awareness of it. The intention is to prevent present and future happiness. And, logically this works. The depressed mind wants past happiness, if the mind has too much present happiness or begins to have hope for future happiness it will be taken away from its primary intention toward a past self and a past life that at one point seemed very real but is no merely an illusion.
Cognitive behavioral techniques abound to help people see how they are preserving their depression. They help the individual get to erroneous thoughts and beliefs perpetuating depression. They help individuals see that their thoughts are creating the depression and if they can become aware of them they can change things. Proven cognitive behavioral techniques are extremely valuable and should be a cornerstone in ones recovery from depression. Intention Therapy is cognitive behavioral it is just that we help the individual to focus on their intentions. Focus on your intentions as a way to bring to your awareness unconscious forces that guide the majority of your actions. All action is preceded by thought and it is intention the feeds thought. There is an overall unconscious intention towards meeting the needs of self. Maslow's hierarchy of needs give a well researched and accepted account of human needs leading all the way up to the self-actualization needs of fully functioning exemplary people.
Here is an interpretation of Maslow's hierarchy of needs I got from Wikipedia, represented as a pyramid with the more basic needs at the bottom.

I won't comment too much further on Maslow's hierarchy of needs, I just wanted to show what some of the basic human needs might be. The clue to intention is the the categorical needs in which the client mostly opperates from. I also wanted to give some idea of the possible layers of intention and the thoughts that form because of them. The intentions are at the left, aIf you noticed the thought before you last ate or planned to eat it was probably something like: "I am hungry". Before the thought was the intention toward survival or if you have an problem with food the intention may have more to do with avoiding pain and an obsession with the pleasure of certain foods. YUMMY DONUTS! I am not poking fun of individuals with food problems, I am just indicating how easy it is to be one of them. The intention to get to the other side of obsession, to feel the pleasure of giving into it, that should be clear to nearly all of us. The consequences have to outweigh the benefits in such a case, sometimes they do, sometimes they don't. To get to the other side of any kind of addictive obsession is extremely difficult. There is an extreme amount of intention to get to the other side of obsession and get a release from the pain of it and feel the pleasure of the object of obsession. I hear some people say they don't understand addicts. I don't know if they are truthful or just in denial first of all. But, if they are being truthful and they have never had a strong obsession toward any object of euphoria, I don't know whether to envy them or feel sorry for them.
Depression seems to have some of the same intention to get to the other side of obsession. But, the obsession is only obtainable in fantasy because one can never really go back to a former self. They can recreate the current self using strategies that have worked in the past but they can never have the self that was in the past because that would require that nothing in their life changed and we all know that everything changes sometimes gradually and sometime suddenly but change is constant.
You can help individuals who are depressed to notice their intentions by listening to them and repeating back when they say things like: "I just want to go back to my life before the accident", "I wish I could have the things I used to", "I want to have my life back"...
People are at a crossroads and their potential for positive change is greatest when they have a strong counter-intention to be free of depression, and they can see that it's not strong enough to overcome depression. They are not clear on what is driving the depression in the form of intention but they will be able to see it because they are open to it.
Don't help people by giving them your preconceived ideas of the intention behind their depression. Help them by letting them see it by reflecting back the thoughts that point to intention. There can certainly be other intentions that guide depression. Since there are secondary gains to depression and the inaction and immobility that go with it the intention might be to have others do what you would rather not. It might be to attract someone who is attracted to a person who is depressed. Be open to whatever comes and don't go with the obvious until it is obvious. It's ok to give people your sense of what is going on with them but don't ever tell them what is going on with them.
Say something like "my sense is there is a time in the past you would like to get back too..." If they say no, leave it alone. They will either later contradict themselves and you can point out the discrepancy, or it may be that you don't know everything. I know I shudder at the thought too, but it is a possibility, is it not? Assuming you know everything gets in the way of therapy, people need to be heard, regardless of whether or not you have heard it all before, and mostly all that is coming out is self delusion. The subtleties of delusive discord constantly present you with opportunities to come at truth from varying perspectives. Because there is usually a little truth in all deception, the better deception usually has the most truth. Anyways truth is relative so what am I really even talking about. It doesn't matter you still have to help people find their truth. And, to find their truth after they leave you they need to have an intention toward mental freedom. They need to have a good taste of that mental freedom and they need to know how to get to freedom when they are encumbered by day to day stuff.